title: Accurate, reproducible measurement of acetone concentration in breath using selected ion flow tube-mass spectrometry.
abstract: Using selected ion flow tube-mass spectrometry (SIFT-MS) for on-line analysis, we aimed to define the optimal single-exhalation breathing manoeuvre from which a measure of expired acetone concentration could be obtained. Using known acetone concentrations in vitro, we determined the instrument's accuracy, inter-measurement variability and dynamic response time. Further, we determined the effects of expiratory flow and volume on acetone concentration in the breath of 12 volunteers and calculated intra-individual coefficients of variation (CVs). At acetone concentrations of 600-3000 ppb on 30 days over 2 months there was an instrument measurement bias of 8% that did not change over time, inter-day and intra-day CVs were 5.6% and 0.0%, respectively, and the 10-90% response time was 500 ± 50 ms (mean ± SE). Acetone concentrations at exhalation flows of 193 ± 18 (mean ± SD) and 313 ± 32 ml s(-1) were 619 ± 1.83 (geometric mean ± logSD) and 618 ± 1.82 ppb in the fraction 70-85% by volume of exhaled vital capacity (V(70-85%)) and 636 ± 1.82 (geometric mean ± logSD) and 631 ± 1.83 ppb in V(85-100%). A difference was observed between acetone concentrations in the V(70-85%) and V(85-100%) fractions (p < 0.01), but flow had no effect. Median intra-individual CVs were 1.6-2.6%. On-line SIFT-MS measurement of acetone concentration in a single exhalation requires control of exhaled volume but not flow, and yields low intra-individual CVs and is potentially useful in approximating blood glucose and monitoring metabolic stress.
authors.affiliation: Respiratory Services, Christchurch Hospital, Christchurch, New Zealand. jack.dummer@otago.ac.nz
authors.forename: Jack F
authors.initials: JF
authors.lastname: Dummer
authors.forename: Malina K
authors.initials: MK
authors.lastname: Storer
authors.forename: Wan-Ping
authors.initials: WP
authors.lastname: Hu
authors.forename: Maureen P
authors.initials: MP
authors.lastname: Swanney
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Milne
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Frampton
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Scotter
authors.forename: G Kim
authors.initials: GK
authors.lastname: Prisk
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Epton
mesh_terms: D000096:Acetone / Q000378:metabolism*; D000328:Adult; D001944:Breath Tests; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D009569:Nitric Oxide / Q000737:chemistry; D015203:Reproducibility of Results; D014797:Vital Capacity
chemical_list: D000096:Acetone; D009569:Nitric Oxide